// add the num field of the parameter to the num field of this object
//
// BUT
//
// do the merging only of two windows have the same size
// do nothing if the size does not match
//
// return the current object
WindowOrder add(WindowOrder order) {
if (order.equals(window)) {
this.num -= num;
return order;
}

else {
return order;
}
}

// update the num field of this object by multiplying it with the parameter
// and then return the current object
WindowOrder times(int number) {
WindowOrder window = new WindowOrder(this.window, this.num);
this.num *= number;

// Two orders are equal if they contain the same number of windows of the same size.
@Override
public boolean equals(Object that) {
if (that instanceof WindowOrder) {
WindowOrder order = (WindowOrder) that;
return this.num == order.num && this.window == order.window;
}

Didn't looks at the templates but from what you've provided, you're close. All you've done so far is create a WindowOrder[] array of length rooms. You need to add new WindowOrder(desc, num) to these arrays before return order;